The present application claims priority to Japanese Application Nos. P11-195241 filed Jul. 9, 1999; P11-216798, filed Jul. 30, 1999; P11-250340 filed Sep. 3, 1999; P11-275919 filed Sep. 29, 1999; and P11-275920 filed Sep. 29, 1999 which applications are incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to a photovoltaic-charged secondary battery device having a storage battery which is chargeable with electricity produced by a photoelectric transducer.
2. Description of the Related Art
In general, a photoelectric transducer is known and referred to as a solar battery, and converts photo energy such as solar energy into electric energy. Unlike conventional fossil fuels, photoelectric transducers do not produce emissions such as carbon dioxide, when generating electric energy from photo energy. Photoelectric transducers can generate electricity semi-permanently because they produce electric energy from solar energy which is the to be almost inexhaustible. Photoelectric transducers are therefore expected to find wider use and greater scale of use, from the global environmental point of view.
However, photoelectric transducers are in many cases do not suitably used as direct power supply of electric appliances, because they exhibit an ample variation of the output electric energy due to large change in the level of photo energy such as solar light which significantly varies according to time. Furthermore, in order for the photoelectric transducers to produce practically usable level of electric energy, large area must be available on such transducers for receiving light rays, because the photo energy such as solar energy is spatially distributed in a highly diluted manner. For these reasons, photoelectric transducers are used to provide only assisting electric power or to charge a storage battery from which electric energy is discharged for use.
In the meantime, current progress in various working and machining technologies have accelerated a trend towards miniaturization of electrical appliances, and various kinds of handy or portable or hand-held devices are becoming available. Such portable or hand-held devices usually operate with power supplied from a dry cell which is a handy and portable power supply.
Photovoltaic-chargeable secondary batteries, which combines the advantages of photoelectric transducers and the convenience of dry cells have been proposed as in Japanese Unexamined Patent Application Publication No. 63-314780 entitled battery and in Japanese Unexamined Patent Application Publication No. 2-73675 entitled cylindrical chargeable solar battery. Such a known photovoltaic-charged secondary battery device consolidates a power-generating photoelectric transducer and a storage battery as a chargeable/dischargeable element into the form of a standard cylindrical cell. Thus, ordinary electric appliances can be activated by electric power derived from photo energy.
Conventional photovoltaic-charged secondary batteries, however, have the following shortcomings. Firstly, it is impossible to use the entire surfaces of the storage battery as the light-receiving surface, because photo energy such as solar energy is usually impinges upon the battery only in one direction. Further, it is impossible to increase the area of the light-receiving surface beyond the total outer surface area of the battery. Consequently, the known photovoltaic-charged secondary battery device requires impractically long charging time or even fails to produce electric energy required for sufficiently charging up the storage battery.
Under these circumstances, the inventors have made an intense study to invent a photovoltaic-charged secondary battery device in which a storage battery is combined with a flexible photoelectric transducer so as to make it possible to use, as a power supply of an ordinary electric appliance, power generated from photo energy such as solar energy. The inventors have filed a patent application on this invention and the application now bears Japanese Patent Application No. 10-351505. Thus, the inventors have succeeded in developing a photovoltaic-charged secondary battery device which has practically satisfactory charging performance and which can suitably be used as power supply of ordinary electric appliances.
However, this photovoltaic-charged secondary battery device still requires improvements in some respects. One major problem is that the photoelectric transducer tends to be damaged and deteriorated in a short time, so that the overall power generating efficiency and, hence, the charging performance are undesirably impaired. This is attributable to the fact that the flexible photoelectric transducer undergoes frequent straightening to develop a large light-receiving area to charge up the battery and, in some cases, frictional contact with other part of the secondary battery device.
Another deficiency to be eliminated is that not a negligible portion of the photoelectric transducer in the unrolled state is shaded to fail to receive light rays, though other portions are sufficiently irradiated with light rays. The shaded portions cannot efficiently generate electric energy, so that the overall power generating efficiency and, hence, the charging performance are impaired.
Still another problem is as follows. The photoelectric transducer has the form of a photoelectric transducer sheet composed of a flexible carrier sheet or substrate and a plurality of photoelectric transducer elements arranged on the sheet. When the photoelectric transducer sheet is unrolled to develop a large light-receiving area, a large external force is applied to the photoelectric transducer sheet. The inventors have found that such a large external force is necessary to overcome resistance which is generated as a result of frictional engagement between the sheet and other parts of the secondary battery device. Repeated application of such a large external force accelerates damaging and deterioration of the photoelectric transducer, resulting in a reduced overall power generating efficiency and, therefore, in inferior charging performance.
A further problem to be solved is as follows. When charging the storage battery, the photoelectric transducer sheet is unrolled to develop a large area for receiving solar light rays. The photovoltaic-charged secondary battery device placed under the sunshine may be heated up to an extraordinary high temperature, posing a risk of blow-off of an internal gas or electrolyte to blow off due to excessive rise of the pressure inside the storage battery. This risk cannot be completely avoided even when users are adequately cautioned, although the probability of occurrence of such n accident is very small. It is therefore necessary to take a measure to protect the photovoltaic-charged secondary battery device against an excessive temperature rise of the storage battery.
Accordingly, an object of the present invention is to provide a photovoltaic-charged secondary battery device having a photoelectric transducer sheet carrying a photoelectric transducer formed thereon and combined with a storage battery, wherein the photoelectric transducer sheet has flexibility and durability sufficient to ensure high charging performance against repeated use.
A second object of the present invention is to provide a photovoltaic-charged secondary battery device having a flexible photoelectric transducer sheet carrying a photoelectric transducer formed thereon, a storage battery, and a peripheral wall member which protects the photoelectric transducer sheet, thereby offering charging performance which is practically satisfactory and which can be maintained for a long time against repeated use.
A third object of the present invention is to provide a photovoltaic-charged secondary battery having a photoelectric transducer sheet which is uncoiled and extracted from a core so as to be exposed to light rays, the transducer sheet generating electrical energy with which a storage battery is charged, wherein the durability of the photoelectric transducer sheet is improved against repeated recoiling and uncoiling, thereby ensuring high and long-lasting power generating efficiency of the photoelectric transducer sheet and, hence, excellent charging performance over a long period of use.
A fourth object of the present invention is to provide a photovoltaic-charged secondary battery device which adopt a safety measure against the use under an unexpectedly high-temperature environment. More specifically, the fourth object is to provide a photovoltaic-charged secondary battery device having a flexible photoelectric transducer sheet and a storage battery to be charged with electric energy generated by the flexible photoelectric transducer sheet, wherein, when the secondary battery device has been heated to an extraordinarily high temperature, electrical connection between the storage battery and an associated member or mechanism is automatically broken or, alternatively, the storage battery is automatically ejected from the secondary battery device. Thus, the forth object is aimed at providing a photovoltaic-charged secondary battery device that can be used safely without any risk of damaging and breakdown of the storage battery, and without causing contamination of environment.
In accordance with a first aspect of the present invention, there is provided a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a chargeable/dischargeable storage battery; and a control circuit for controlling the charging and discharging operations of the storage battery; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; the photovoltaic-charged secondary battery device further comprising a polymeric cover film formed on at least the light-receiving surface of the photoelectric transducer sheet.
With these features, it is possible to obtain a photovoltaic-charged secondary battery device which maintains high charging performance for a long time against repeated use, by virtue of the combination between the flexible and durable photoelectric transducer sheet and a storage battery.
Preferably, the photoelectric transducer sheet has a plurality of photoelectric transducer elements formed thereon and arranged in parallel with the longitudinal axis thereof, the photoelectric transducer elements being electrically connected in series one to another. This feature eliminates any reduction in the overall power generating efficiency of the photoelectric transducer sheet which hitherto has been unavoidable due to the fact that part of the photoelectric transducer sheet fails to receive light rays as it remains inside the photovoltaic-charged secondary battery device without being fully extracted.
It is also preferred that the storage battery is accommodated in a space inside the core, and that, when the photoelectric transducer sheet is fully rolled on the core, the photovoltaic-charged secondary battery device generally has dimensions and shape of a predetermined cylindrical standard battery.
The storage battery preferably has a discharge voltage which is not less than 0.6 V and not higher than 1.9 V.
The storage battery is preferably detachable from the space in the core.
The aforementioned first object of the present invention can also be achieved by a second aspect of the present invention. According to the second aspect of the present invention, there is provided a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a chargeable/dischargeable storage battery; and a control circuit for controlling the charging and discharging operations of the storage battery; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; wherein the photoelectric transducer sheet is arranged such that, when the photoelectric transducer sheet is rolled on the core, a light-receiving surface of the photoelectric transducer sheet faces outward of the roll.
With these features, it is possible to obtain a photovoltaic-charged secondary battery device which maintains high charging performance for a long time against repeated use, by virtue of the combination between the flexible and durable photoelectric transducer sheet and a storage battery.
Preferably, this photovoltaic-charged secondary battery device further comprises a polymeric cover film formed on at least the light-receiving surface of the photoelectric transducer sheet. Such a polymeric cover film effectively suppresses damaging and deterioration of photoelectric transducer elements on the photoelectric transducer sheet. Preferably, the photoelectric transducer sheet has a plurality of photoelectric transducer elements formed thereon and arranged in parallel with the longitudinal axis thereof, the photoelectric transducer elements being electrically connected in series one to another. This feature eliminates any reduction in the overall power generating efficiency of the photoelectric transducer sheet which hitherto has been unavoidable due to the fact that part of the photoelectric transducer sheet fails to receive light rays as it remains inside the photovoltaic-charged secondary battery device without being fully extracted.
Preferably, the storage battery is accommodated in a space inside the core. It Is also preferred that, when the photoelectric transducer sheet is fully rolled on the core, the photovoltaic-charged secondary battery device generally has dimensions and shape of a predetermined cylindrical standard battery.
The storage battery preferably has a discharge voltage which is not less than 0.6 V and not higher than 1.9 V. It is also preferred that the storage battery is detachable from the space in the core, and that the storage battery has the dimensions and the shape of a predetermined cylindrical standard battery.
In order to achieve the aforesaid second object of the present invention, according to a third aspect of the present invention, there is provided a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a chargeable/dischargeable storage battery; and a control circuit for controlling the charging and discharging operations of the storage battery; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form, wherein the photovoltaic-charged secondary battery device further comprises: substantially flat, disk-shaped upper and lower flanges provided on both ends of the core; and a peripheral wall member disposed between and rotatably supported by the upper and lower flanges, the peripheral wall member and the core defining therebetween an annular space for accommodating the photoelectric transducer sheet rolled on the core, the peripheral wall member having a slit through which the photoelectric transducer sheet is extracted and retracted, such that rotation of the peripheral wall member causes the photoelectric transducer sheet to be retracted into the annular space and rolled on the core, the photoelectric transducer sheet having an inner end region having a length large enough to space the inner end of effective photovoltaic portion of the photoelectric transducer sheet to be sufficiently spaced apart from the slit when the photoelectric transducer sheet is extracted from the annular space.
In the known photovoltaic-charged secondary battery device, a problem is encountered in that the overall power generating efficiency of the photoelectric transducer sheet is deteriorated due to the fact that part of the photovoltaic portion of the photoelectric transducer sheet is shaded to fail to receive sufficient light rays. This problem is overcome by the above-described feature of the third aspect of the present invention.
It is preferred that, when the photoelectric transducer sheet is fully rolled on the core, the photovoltaic-charged secondary battery device generally has dimensions and shape of a predetermined cylindrical standard battery.
It is also preferred that the storage battery has a discharge voltage which is not less than 0.6 V and not higher than 1.9 V, and that the storage battery is detachable from the core.
In order to achieve the aforementioned third object of the present invention, in accordance with a fourth aspect of the present invention, there is provided a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a chargeable/dischargeable storage battery; and a control circuit for controlling the charging and discharging operations of the storage battery; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; the photovoltaic-charged secondary battery device further comprising: substantially flat, disk-shaped upper and lower flanges provided on both ends of the core; and a peripheral wall member disposed between and rotatably supported by the upper and lower flanges, the peripheral wall member and the core defining therebetween an annular space for accommodating the photoelectric transducer sheet rolled on the core, the peripheral wall member having a slit through which the photoelectric transducer sheet is extracted and retracted, such that rotation of the peripheral wall member causes the photoelectric transducer sheet to be retracted into the annular space and rolled on the core, the peripheral wall member further having a plurality of projections on the inner surface thereof.
A photovoltaic-charged secondary battery device as a modification of this fourth aspect of the present invention which comprises: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a chargeable/dischargeable storage battery; and a control circuit for controlling the charging and discharging operations of the storage battery; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; the photovoltaic-charged secondary battery device further comprising: substantially flat, disk-shaped upper and lower flanges provided on both ends of the core; and a peripheral wall member disposed between and rotatably supported by the upper and lower flanges, the peripheral wall member and the core defining therebetween an annular space for accommodating the photoelectric transducer sheet rolled on the core, the peripheral wall member having a slit through which the photoelectric transducer sheet is extracted and retracted, such that rotation of the peripheral wall member causes the photoelectric transducer sheet to be retracted into the annular space and rolled on the core, the photoelectric transducer sheet having a plurality of projections formed on the surface thereof facing the inner surface of the peripheral wall member.
In accordance with the fourth aspect of the present invention, the photoelectric transducer sheet can be extracted while causing the surface of the photoelectric transducer sheet sliding on the apices of the projections formed on the inner surface of the peripheral wall member, without allowing the sheet to make a surface-to-surface contact therewith. In the modification, the photoelectric transducer sheet can be extracted with the projections formed thereon sliding on the inner surface of the peripheral wall member, without making a surface-to-surface contact therewith. This eliminates the necessity of applying an impractically large puling force on the photoelectric transducer sheet, unlike the known photovoltaic-charged secondary battery device, thus avoiding damaging or rapid deterioration of the photoelectric transducer sheet attributable to the application of large pulling force. It is also to be noted that, in the fourth aspect of the invention, the dynamic frictional force acting between the photoelectric transducer sheet and the projections on the inner surface of the peripheral wall member is significantly smaller than that developed in the known photovoltaic-charged secondary battery device due to the surface-to-surface contact therebetween. Likewise, in the modification, the dynamic frictional force acting between the photoelectric transducer sheet and the projections on the photoelectric transducer sheet and the inner surface of the peripheral wall member is significantly smaller than that developed in the known photovoltaic-charged secondary battery device due to the surface-to-surface contact therebetween. This also contributes to prevention of damaging of the photoelectric transducer sheet.
Thus, the fourth aspect and the modification overcomes the problem of the known art: namely, reduction in the overall power generating efficiency of the photoelectric transducer sheet and a consequent reduction in the charging performance attributable to the application of a large pulling force on the photoelectric transducer sheet.
It is preferred that, when the photoelectric transducer sheet is fully rolled on the core, the photovoltaic-charged secondary battery device generally has dimensions and shape of a predetermined cylindrical standard battery. It is also preferred that the storage battery has a discharge voltage which is not less than 0.6 V and not higher than 1.9 V. The storage battery is preferably detachable from the core. In the fourth aspect of the invention, the photoelectric transducer sheet is preferably arranged such that, when it is rolled on the core, its light-receiving surface faces inward of the roll. In contrast, in the modification, the projections are formed on the surface of the photoelectric transducer sheet opposite to the light-receiving surface, and the photoelectric transducer sheet is rolled such that its light-receiving surface faces inward of the roll.
In order to achieve the aforementioned fourth object of the present invention, in accordance with a fifth aspect of the present invention, there is provided a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a detachable storage battery chargeable through the photoelectric transducer sheet and capable of discharging; a control circuit for controlling the charging and discharging operations of the storage battery; and a temperature-responsive mechanism; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; the temperature-responsive mechanism being operable to break electrical connection between the storage battery and an associated member when the temperature thereof has been raised to a predetermined high temperature.
A photovoltaic-charged secondary battery device as an alternative arrangement of the fifth aspect comprises: a photovoltaic-charged secondary battery device comprising: a cylindrical core; a flexible photoelectric transducer sheet extractably rolled on the core; a detachable storage battery chargeable through the photoelectric transducer sheet and capable of discharging; a control circuit for controlling the charging and discharging operations of the storage battery; and a temperature-responsive mechanism; the photovoltaic-charged secondary battery device with the photoelectric transducer sheet fully rolled on the core generally exhibiting a substantially cylindrical form; the temperature-responsive mechanism being operable to cause the storage battery to be moved apart from a predetermined position when the temperature thereof has been raised to a predetermined high temperature.
In accordance with a practical form of the fifth aspect of the present invention, there is provided a photovoltaic-charged secondary battery device which comprises: a cylindrical core 2; a flexible photoelectric transducer sheet 3 which is extractably rolled on the core 2; a detachable and dischargeable/chargeable storage battery 4 chargeable through the photoelectric transducer sheet 3; and a control circuit 5 for controlling the discharging and charging operations. The photovoltaic-charged secondary battery device generally exhibits a substantially cylindrical form when the photoelectric transducer sheet 3 is fully rolled on the core 2. The photovoltaic-charged secondary battery device 1 further comprises a conductive spring 31 provided at one axial end of the core 2 and held in electrical connection with one 9 (or 8) of the two electrode terminals of the photovoltaic-charged secondary battery device; a battery insert hole 91 formed in the other axial end of the core 2; a lid mount member 9a provided on the edge of the battery insert hole 91 and serving also as the other 9 (or 8) of the electrode terminals of the photovoltaic-charged secondary battery device; a lid member 92 made of an electrically conductive material and hinged to the lid mount member 9a; and an electrically conductive lid locking member 93 attached to the lid mount member 9a and reversibly deformable in response to change in temperature; wherein the storage battery 4 is accommodated in a space defined in the core 2 with the lid member 92 locked in a closing position by the lid locking member 93, such that one 4a (or 4b) of its electrode terminals is pressed by the spring 31 while the other 4b (or 4a) of the electrode terminals held in electrical connection with the other 9 (or 8) of the electrode terminals of the photovoltaic-charged secondary battery device via the lid member or via the lid locking mechanism 93, the lid locking mechanism being thermally deformable to unlock the lid member 92 when the temperature thereof has been raised to a predetermined temperature.
In accordance with the first embodiment and its modification described above, when the temperature of the photovoltaic-charged secondary battery device has been raised to an abnormally high level, electrical connection between the photovoltaic-charged secondary battery device and associated member or mechanism is automatically broken or, alternatively, the storage battery is automatically ejected from the photovoltaic-charged secondary battery device. It is therefore possible to prevent damaging or breakdown of the photovoltaic-charged secondary battery device and associated devices, while preventing contamination of environment.
In the practical embodiment of the photovoltaic-charged secondary battery device in accordance with the fifth aspect, the spring 31 provided on one axial end of the core 2 constantly urges the storage battery 4, tending to eject the storage battery 4 from the space inside the core 2 through the battery insert hole 91. When the temperature of the photovoltaic-charged secondary battery device and, hence, of the storage battery 4 has been raised to an abnormally high temperature, the lid locking mechanism 33 is thermally deformed to unlock the lid member 92, thereby the storage battery 4 is forced out of the core by the force of the spring 31. This results in (1) automatic breakage of the electrical connection between the photovoltaic-charged secondary battery device and associated member or mechanism or, alternatively, automatic ejection of the storage battery from the photovoltaic-charged secondary battery device. It is therefore possible to prevent damaging or breakdown of the photovoltaic-charged secondary battery device and associated devices, while preventing contamination of environment.
Preferably, when the photoelectric transducer sheet is fully rolled on the core, the photovoltaic-charged secondary battery device generally has dimensions and shape of a predetermined cylindrical standard battery. It is also preferred that the storage battery has a discharge voltage which is not less than 0.6 V and not higher than 1.9 V. It is also preferred that the storage battery has the dimensions and shape of a predetermined cylindrical standard battery. The lock mechanism used in the practical embodiment described before is preferably constituted by a leaf-spring-shaped member formed from a bimetal composed of a shape memory alloy and an alloy which has high resiliency.
The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments when the same is read in conjunction with the accompanying drawings.